#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <unistd.h>
#include <pthread.h>
#include <sched.h>

int ticket = 0;
pthread_mutex_t mutex;
pthread_cond_t cond = PTHREAD_COND_INITIALIZER;


void *route(void *arg)
{
    char *id = (char *)arg;
    // while (1)
    // {
    //     pthread_mutex_lock(&mutex);
    //     if (ticket > 0)
    //     {
    //         usleep(1000);
    //         printf("%s sells ticket:%d\n", id, ticket);
    //         ticket--;
    //         pthread_mutex_unlock(&mutex);
    //     }
    //     else
    //     {
    //         pthread_mutex_unlock(&mutex);
    //         printf("%s wait on cond!\n", id);
    //         pthread_cond_wait(&cond, &mutex); //醒来的时候，会重新申请锁
    //         printf("%s 被叫醒了\n", id);    
    //     }
    //     pthread_mutex_unlock(&mutex);
    // }
    while (1) {
        pthread_mutex_lock(&mutex);
        
        // 必须用 while 检查条件
        while (ticket <= 0) {
            printf("%s wait on cond!\n", id);
            if (pthread_cond_wait(&cond, &mutex) != 0) {
                perror("cond_wait failed");
                pthread_mutex_unlock(&mutex);
                break;
            }
            printf("%s 被叫醒了\n", id);
        }
    
        if (ticket > 0) {
            printf("%s sells ticket:%d\n", id, ticket);
            ticket--;
            pthread_mutex_unlock(&mutex);  // 先解锁
            usleep(1000);                 // 后休眠
        } else {
            pthread_mutex_unlock(&mutex);
        }
    }
    return nullptr;
}

int main(void)
{
    pthread_t t1, t2, t3, t4;

    pthread_mutex_init(&mutex, NULL);

    pthread_create(&t1, NULL, route, (void *)"thread 1");
    pthread_create(&t2, NULL, route, (void *)"thread 2");
    pthread_create(&t3, NULL, route, (void *)"thread 3");
    pthread_create(&t4, NULL, route, (void *)"thread 4");

    int cnt = 10;

    while(true)
    {
        sleep(2);
        ticket += cnt;
        printf("主线程放票喽, ticket: %d\n", ticket);
        pthread_cond_signal(&cond);
    }


    pthread_join(t1, NULL);
    pthread_join(t2, NULL);
    pthread_join(t3, NULL);
    pthread_join(t4, NULL);
    pthread_mutex_destroy(&mutex);
}